On January 8th a preliminary study published online in the journal Neurology found that even when healthy young men were sleeping enough for only one night, their blood levels of tau protein, a biomarker of Alzheimer’s disease, increased.
Tau protein is a protein found in neurons that accumulates in the brains of Alzheimer’s patients and can begin to develop in the brain decades before symptoms of the disease appear. Previous studies in older adults have shown that sleep deprivation can increase levels of tau protein in the cerebrospinal fluid, and head trauma can also increase the circulating concentration of tau protein in the blood.
Study author Jonathan Cedernas, M.D., of Uppsala University in Sweden, said: ‘Sleep deprivation is increasing in daily life, and our exploratory research shows that even young, healthy people can increase levels of tau protein in their blood. This suggests that this sleep deprivation may have harmful effects over time. “
The study involved 15 healthy, normal-weight men, with an average age of 22, who reported regularly getting seven to nine hours of high-quality sleep a night.
The study is divided into two phases. At each stage, these people are observed in the laboratory for two days and two nights of rigorous meal and activity planning. Blood samples are collected at night and again in the morning. At one stage, participants were allowed to sleep well for two nights. At another stage, participants were allowed to get a good night’s sleep on the first night, followed by the second night of sleep deprivation. During sleep deprivation, the lights are on as participants sit in bed playing games, watching movies, or chatting.
The researchers found that after less than one night’s sleep, men’s levels of tau protein increased by an average of 17 percent, while tau protein levels increased by an average of 2 percent after a good night’s sleep.
The researchers also looked at four other biomarkers associated with Alzheimer’s disease, but levels did not change between a good sleep and a sleepless night.
Dr Sedness said: “Although higher levels of tau protein in the brain are not good, we do not know what higher levels of tau protein in the blood represent in the absence of sleep. When neurons are active, the production of tau proteins in the brain increases, and higher levels of tau proteins in the blood may reflect that these tau proteins are being removed from the brain, or they may reflect an increase in the level of tau protein sinin in the brain. “
“Future studies will require further research on this and determining how long these changes in tau protein last, and determining whether changes in tau in the blood reflect a mechanism through which repeated exposure to restrictive, interruptive or irregular sleep may increase the risk of dementia.” These studies could provide key information on whether sleep-oriented interventions should start from an early age to reduce a person’s risk of developing dementia or Alzheimer’s disease. “